System Operation Check

A/C SYSTEM CHECK

Chart A:

Charts B and C:

Chart D:

Chart E:

If outside air temperature is above 21°C (70°F), the following procedure can he used to quickly determine whether the air conditioning refrigeration system has the proper charge of R- 12. This check can be made in a few minutes, simplifying system diagnosis by localizing the problem of a low refrigerant charge or eliminating that possibility.

The engine must be at normal operating temperature and running at normal idle speed. The hood and all body doors must be open. The air conditioning controls must be set for outside air induction. high blower speed and the coldest temperature setting.

When the compressor is operating. the technician should use a hand to feel the temperature of the evaporator inlet and outlet pipes. The evaporator inlet pipes should feel hot to the touch: the evaporator outlet pipe should feel cold. If the evaporator inlet pipe is cooler than the outlet pipe. or if the inlet pipe has a coating of frost. a low refrigerant charge is indicated. The technician should add 0.11 kg (0.250 lbs.) of R-12 and allow the system to stabilize. This should be repeated as necessary until the evaporator pipes are the correct temperature. Once this has been determined. another (0.40 kg (0.888 lbs.) of R-12 should be added to the refrigeration system.